In Windows Vista, you do not have immediate access to the G_D account (Administrator). When logging into Windows Vista, you do not have the option of using this account. I believe Microsoft is doing this to protect the average user from the havoc the Administrator account can cause. Some installations and programs require this account. So how do I enable it?
From the Start menu, simply right-click on Computer and choose Manage. Next, expand Local Users and Groups and select the Users folder. The final step is to right-click on the Administrator login and choose properties. Clear the Account is Disabled checkbox and you have now enabled your Administrator account.